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Thursday, May 23, 2013

Explosion On The Sun Exposes Earth To An Ongoing Radiation Storm

SUBSIDING RADIATION STORM: A solar radiation storm in progress around Earth is slowly subsiding. It currently ranks S2 (moderate) on NOAA storm scales, which means that satellites in Earth orbit could experience "single event upsets" in their electronic systems. The radiation storm is also a source of noise in spacecraft cameras, giving their images a snowy appearance (see below)

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M5-CLASS EXPLOSION: The ongoing radiation storm got started on May 22nd when the magnetic canopy of sunspot AR1745 exploded. The blast produced an M5-class solar flare and hurled a magnificent CME over the sun's western limb:

Credit: the Solar and Heliospheric Observatory (SOHO)

The movie of the CME is very "snowy." That is caused by high-energy solar protons striking the CCD camera in SOHO's coronagraph. Each strike produces a brief snow-like speckle in the image. This hailstorm of solar protons is what forecasters mean by "radiation storm."

Although the explosion was not squarely Earth-directed, the CME will likely be geoeffective. The expanding cloud appears set to deliver a glancing blow to Earth's magnetic field on May 24th around 1200 UT. According to NOAA forecast models, the impact will more than double the solar wind plasma density around Earth and boost the solar wind speed to ~600 km/s. High-latitude sky watchers should be alert for auroras.

The FINANCIAL -- A large solar storm could leave tens of millions of people in North America without electrical power for several months, if not years, potentially costing trillions of dollars, according to Lloyd’s latest emerging risks report: Solar Storm Risk to the North American Electric Grid.

Large geomagnetic storms, while relatively rare, can create a massive surge of current, potentially overloading the electric grid system and damaging expensive, and critical, transformers, according to report.

A large solar storm in 1989 triggered the collapse of Quebec’s electrical power grid– leaving six million Canadians without power for nine hours – while a smaller storm in 2003 caused blackouts in Sweden as well as damage to transformers in South Africa (transformers at that latitude were previously thought to be immune from such damage).

However, much bigger and potentially more disruptive events are possible. The Carrington Event of 1859 is widely regarded as the most extreme space weather event on record. It is thought that such an event today would affect between 20-40 million people in the US with power cuts lasting from several weeks to 1-2 years. The economic costs would be catastrophic – estimated at between $0.6 and $2.6trn.

Carrington-level extreme geomagnetic storm is rare. Historical records suggest a return period of 50 years for Quebec-level storms, and 150 years for very extreme storms, such as the Carrington Event. However, far weaker storms still pose a significant risk.

Governments are waking up to the risk and taking the threat of geomagnetic storms seriously.

A severe geomagnetic storm event in North America could have significant implications for the insurance industry. Sustained power outages could expose insurers to significant business interruption claims, although exactly how cover for such an event would respond is uncertain.

Extreme solar weather is a huge potential threat for power companies and their insurers, according to John Chambers, deputy active underwriter at Aegis London, a specialist insurer of power companies.

"Insurers and risk managers have made some progress in identifying geographical areas and types of equipment that could be more susceptible to loss. However, the lack of recent claims has meant that the issue is lower down the agenda for insurers than perhaps it should be and has made it harder for risk managers to get the appropriate capex budgets for risk mitigation," he says.

“Specialist power insurers should be looking at wordings and the use of sub-limits and stand-alone coverage, although they are open to engaging with other bodies to look at ways of improving resilience and managing risk,” he adds.

“Geomagnetic storms present a huge potential risk with important implications for both insurers and society,” says Smith. “Insurers need to evaluate the potential impact of geomagnetic storms on the market, as well as work with governments and energy companies on ways to mitigate the risk at a society level,” he says.

UPDATE 16:30 p.m. EDT: The M7-class flare was also associated with a coronal mass ejection or CME, another solar phenomenon that can send billions of tons of particles into space. While this CME was not Earth-directed, it has combined with an earlier CME, and the flank of the combined cloud may pass Earth. Particles from the CME cannot travel through the atmosphere to harm humans on Earth, but they can affect electronic systems in satellites and on the ground.

› View largerThis image, captured at 11:06 a.m. EDT on May 22, 2013, from the ESA/NASA Solar and Heliospheric Observatory shows theconjunction of two coronal mass ejections streaming away from the sun. This image is what's known as a coronagraph, in which the light of the sun is blocked in order to make its dimmer atmosphere, the corona, visible. Credit:ESA and NASA/SOHO

Experimental NASA research models, based on observations from NASA’s Solar Terrestrial Relations Observatory and ESA/NASA’s Solar and Heliospheric Observatory show that the first CME began at 5:12 a.m. EDT, leaving the sun at about 400 miles per second. The second CME began at 9:24 a.m. EDT, leaving the sun at speeds of around 745 miles per second.

Earth-directed CMEs can cause a space weather phenomenon called a geomagnetic storm, which occurs when they funnel energy into Earth's magnetic envelope, the magnetosphere, for an extended period of time. In the past, geomagnetic storms caused by CMEs of this strength have usually been mild.

The NASA models also show that the combined CMEs will pass by the STEREO-A spacecraft and its mission operators have been notified. If warranted, operators can put spacecraft into safe mode to protect the instruments from the solar material.

NASA and NOAA – as well as the US Air Force Weather Agency (AFWA) and others -- keep a constant watch on the sun to monitor for space weather effects such as geomagnetic storms. With advance notification many satellites, spacecraft and technologies can be protected from the worst effects

NOAA's Space Weather Prediction Center (http://swpc.noaa.gov) is the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

› View larger imageNASA’s Solar Dynamics Observatory captured this image of a solar flare on the right side of the sun on May 22, 2013. This image shows light in the 131 Angstrom wavelength, a wavelength that shows material heated to intense temperatures during a flare and that is typically colorized in teal. Credit: NASA/SDO

The sun emitted a mid-level solar flare on the morning of May 22, 2013. The flare peaked at 9:38 a.m. EDT and was classified as an M7. M-class flares are the weakest flares that can still cause some space weather effects near Earth. In the past, they have caused brief radio blackouts at the poles.

Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. This disrupts the radio signals for as long as the flare is ongoing, anywhere from minutes to hours.

Increased numbers of flares are quite common at the moment, since the sun's normal 11-year activity cycle is ramping up toward solar maximum, which is expected in late 2013. Humans have tracked this solar cycle continuously since it was discovered in 1843, and it is normal for there to be many flares a day during the sun's peak activity.

NOAA's Space Weather Prediction Center (http://swpc.noaa.gov) is the U.S. government's official source for space weather forecasts, alerts, watches and warnings. Updates will be provided as they are available on the flare and whether there was an associated coronal mass ejection or CME, another solar phenomenon that can send solar particles into space and affect electronic systems in satellites and on Earth.

› Download animated gifThese images of a solar flare were captured by NASA’s Solar Dynamics Observatory on May 22, 2013. This image shows light in the 131 Angstrom wavelength, a wavelength that shows material heated to intense temperatures during a flare and that is typically colorized in teal. Credit: NASA/SDO/GSFC

Geomagnetic storm

A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field which interacts with theEarth's magnetic field. The increase in the solar wind pressure initially compresses the magnetosphere and the solar wind's magnetic field interacts with the Earth’s magnetic field and transfers an increased energy into the magnetosphere. Both interactions cause an increase in movement of plasma through the magnetosphere (driven by increased electric fields inside the magnetosphere) and an increase in electric current in the magnetosphere and ionosphere.

During the main phase of a geomagnetic storm, electric current in the magnetosphere creates a magnetic force which pushes out the boundary between the magnetosphere and the solar wind. The disturbance in the interplanetary medium which drives the geomagnetic storm may be due to a solar coronal mass ejection (CME) or a high speed stream (co-rotating interaction region or CIR)[1] of the solar wind originating from a region of weak magnetic field on the Sun’s surface. The frequency of geomagnetic storms increases and decreases with the sunspot cycle. CME driven storms are more common during the maximum of the solar cycle and CIR driven storms are more common during the minimum of the solar cycle.